Print head shifting mechanism

ABSTRACT

An electromagnetically controlled shifting mechanism for aligning one of a plurality of type bands with a printing position. The shifting mechanism includes selectively energizable electromagnets that attract a pivotably mounted linkage which is connected to the shaft which supports the print head. The electromagnets are located two above and two below the linkage so that by the energization of various combinations of the electromagnets the print head can be shifted between the four horizontal printing bands.

United States Patent 1191 Perez 1451 July 3,1973

[ PRINT HEAD SHIFTING MECHANISM Guillermo Perez, Bloomfield, NJ.

[73] Assignee: Litton Business Systems, Inc.,

Orange, NJ.

[75] Inventor:

[22] Filed: Nov. 2, 1970 [21] Appl. No.: 86,159

3,605,978 9/1971 Kawano 178/34 X 2,939,912 6/1960 Durkee 178/34 3,517,124 6/1970 Rekewitz et al. 178/34 Primary Examiner-Edgar S. Burr Attorney-Norman Friedman, Stephen E. Feldman, Morris 1. Pollack, Arthur T. Groeninger and Philip Furgang [57] ABSTRACT An electromagnetically controlled shifting mechanism for aligning one of a plurality of type bands with a printing position. The shifting mechanism includes selectively energizable electromagnets that attract a pivotably mounted linkage which is connected to the shaft which supports the print head. The electromagnets are located two above and two below the linkage so that by the energization of various combinations of the electromagnets the print head can be shifted between the four horizontal printing bands.

11 Claims, 8'Drawing Figures mm ms SHEEI 1 0f 3 INVENTOR GUILLERMO PEREZ ATTORN EY PAIENIEnJuL3 I975 3.743.073

sum 2 or 3 iZfJIjjJJjJJI y F 1" ma I06 INVENTOR GUILLERMO PEREZ ATTORNEY PATENIEQJUL3 191s 3. 743073 saw 3 or 3 INVENTOR GUILLERMO PEREZ ATTORNEY PRINT HEAD SI-IIFTING MECHANISM BACKGROUND OF THE INVENTION In printing mechanisms and especially high speed printing mechanisms it is very important to have a mechanism that will function at these high speeds to shift the print head from one horizontally disposed type band to the next. This becomes especially important when there are more than two type bands as in the case of four type bands, one disposed above the other. Since the entire mechanism is operating at high speeds and very often the mechanism has a print head which prints on the fly, it is most important to have a mechanism which can operate reliably at high speeds and instantaneously shift the print head from any type band to any other type band. Various mechanisms have been tried before but these generally result in very slow operation that cannot keep pace with the speed needed in a high speed printer. Thus, a simple and efficient shifting mechanism for a print head that has multiple bands of type is needed for use in high speed printers.

SUMMARY OF THE INVENTION A shifting mechanism for a print head in a high speed printer wherein four electromagnets operate in conjunction with a linkage mechanism which is attached to the print head to shift the print head by employing various combinations of the electromagnets to place any one of four bands on the print head in a printing position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an overall side view of the shifting mechanism in conjunction with the print head and part of the print head actuating mechanism.

FIG. 2 is a plan view of the mechanism of FIG. 1.

FIG. 3 is a view of the shifting mechanism of FIG. 1 with printing mechanisms removed for clarity.

FIG. 4 is a plan view of FIG. 3 with a part of the supporting mechanism removed.

FIG. 5 is a view of the important components of the shifting mechanism with the lowest type band print head in printing position.

FIG. 6 is a view of the mechanism of FIG. 5 with the type band next to the lowest type band in printing position.

FIG. 7 is a view of the mechanism of FIG. 5 with the type band next to the highest band in printing position.

FIG. 8 is a view of the mechanism of FIG. 5 with the highest type band in printing position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The construction includes the overall support member l, a supporting and transporting member on which the shifting mechanism 2 of this invention is supported and also on which the printing mechanism 3 and the rotational aligning mechanism (a stepping motor) 4 is positioned. This entire mechanism is constructed to be transported horizontally along the printing platen (shown by dotted circle 5). It is supported in this movement by shaft 6, which is part of the supporting structure of the printer and above which it moves by rollers 12 and 13, which ride on rail which is also part of the supporting structure of the printer. A Suitable bearing is positioned between the main support 1 and the shaft 6. The mechanism to transport the print head mechanism along the platen, the mechanism to rotate the print head by use of the stepping motor and mechanism to actuate the print head are all described in detail in US. Pat. Nos. 3,461,996, REED OPERATED PRINTER, and 3,493,091, PRINT HEAD SHIFT MECHANISM, both of which are owned by the assignee of the present application.

. Now, briefly describing the operation of these mechanisms before going into a detailed description of the shifting mechanism of this invention; the stepping motor 4 rotates the print head about the axis of shaft 14 as shown in FIG. 2 to align the proper vertical column of letters with the printing portion. Suitable mechanism is also provided (not shown) to move the entire mechanism along the platen by a suitable tape and pulley mechanism which is only partially shown by pulleys 16 and 18 and tape 20. This is described in more detail in the aforementioned patents; by pulling the tape the entire printing unit can be shifted along the platen.

The print head firing mechanism which is an on the fly" printing mechanism consists of many parts which are also not described in this application but are shown in the aforementioned patents. As to the parts of this mechanism that are shown, tape 22 goes partially around movable pulley 24 and fixed pulleys 23 and 25. As shown in FIG. 2 it goes around the right side of pulley 23 and the left side of pulley 24, and the right side of pulley 25. A yoke 28 is connected from pulley 24 to another yoke 30 by means of pins 32. The latter yoke as shown in FIG. 1, holds the print head 35 in position. Shaft 14 on which the print head is mounted passes through an opening in this yoke 30. Thus, the interconnection of yokes 30 and 28 connects pulley 24 to print head 35.

When printing is desired, tape 22 is pulled taut. Since pulleys 23 and 25 are fixed the tension in tape 22 will cause moveable pulley 24 to move forwardly (to the right in FIGS. 1 and 2), this will cause yoke 28 and thereby yoke 30 to move forwardly (towards the printing platen) since the print head shaft 14 is supporting within yoke 30. This movement will cause the print head to move to the right as shown in FIG. 1 and impact platen 5. The first part of this motion of the print head towards the platen is caused by the pulling of tape 22 taut. However, this only causes the initial movement towards the platen. The final movement and the actual impact is in free flight, tape 22 is only pulled a small amount, an insufficient amount to cause the print head to impact against the platen. The remaining movement is the free flight movement of yoke 30 and the print head and print head shaft about pivots 42; the printing is thus free flight printing.

In the printing operation shaft 36 of pulley 25 pushes against shaft 39 and causes the compression of spring 38 which surrounds this shaft. This shaft and spring are supported by right angle member 40, which is affixed to the main section 1 of the mechanism. Thus as the print head goes forward and as pulley 24 goes forward shaft 39 will also go forward causing compression of spring 38. This force built up in spring 38 will cause the print head to return to the position as shown in FIG. 1 after the printing has taken place.

As aforementioned, stepping motor 4 rotates shaft 14 to bring the proper column of type faces on the print head 35 into printing position. It will also be noted that there is a suitable ball and socket or other coupling between the stepping motor print shaft and shaft 14. For

example, see FIG. 7 of the aforementioned patents. This coupling is located so that the print head and shaft can move in free flight and still be indexed by the stepping motor.

The previous description has concerned itself with the parts of the printer which are not part of this invention. These parts are, as aforementioned, fully disclosed in US. Pat. Nos. 3,493,091 and 3,461,996. Now, referring to the essence of this invention the print head shift mechanism, The mechanism consists of four electromagnets 51,52, 53, and 54 which coact with a first member, a center linkage 56 and are supported by U shaped members 58, 60, 62, and 64. The U shaped members are themselves held in place by being secured to flanges 64 and 66 of main member 1. There are also four short links used for adjustment, three of which are shown 68, 70, and 72. These small links are held in place by being fastened to the flange and to the U shaped members by nuts and bolts. The U" shaped members are attached to the main member with these short links so that they can be tilted slightly to adjust the position of the electromagnets for proper operation of the mechanism, as will be described in more detail subsequently.

The electromagnets each consist of a copper wire winding around a soft metal core. This soft metal core extends from the center of the wire winding to between the U shaped members to which it is attached. Suitable nuts and bolts 76 and 78 pass through the U shaped members and through the metal core to aid in holding the electromagnets in position. Plastic flanges 80 and 82 are provided below and above the wire windings to help keep the wire in place and prevent the unwinding thereof. A suitable insulating tape is provided around the windings for protection, and also electrical leads (not shown) are provided from each of the electromagnets to a power supply to insure their actuation. At the end of the U shaped members 58, 62, etc. opposite the end that is attached to flange 64 and 66 there are bolt and link arrangements 90 and 92 for supporting springs as will be described hereinafter. The bolts fit through a hole in pivoted bars 91. These bars which are pivoted by means of studs 93 which extend from the bar and project through holes in the U shaped members. These bolts have a nut-like link 92 screwed onto their end. Extending from an opening in these bolts to the center linkage are springs 95. These springs are balanced so as to keep the central linkage in a central position spaced equadistantly from the heads 55 of the electromagnets, as will be described in more detail hereinafter. The bolt and linkage arrangement provides for increasing or decreasing the tension on each spring so that they remain balanced.

The center linkage itself consists of a second and third member, two small rectangular members 98 and 100 respectively, each of which are constructed of a magnetically attractable iron and have a main central part 102 and an extending flange 104. The springs 95 are connected to these extending flanges by being placed through openings 105 in each of them. Second and third members 98 and 100 are each connected to main supporting member 1 by means of pins 106 and 108. These pins fit into fittings 107 and 109 to actually hold them to member 1. The pins are connected so as to permit the two smaller members 98 and 100 to pivot in a vertical plane (perpendicular to the paper in FIG. 4) about these pivot pins. The other ends of each of these members 98 and are connected to two long members 110 and 112. These members which are thin in cross sections as shown in FIG. 4 connect the small members 98 and 100 with the shaft 14 on which the print head is mounted. Each of these long members is permantly affixed to the two small members 98 and 100 by means of pins 114 and 116. The pins are mounted so that the small members 98 and 100 can rotate in a vertical plane about the pins. Thus it will be appreciated that the movement of members 98 and 100 can only be in a vertical plane and is further limited by the two sets of pins, pins 108 and 106, and 114 and 116, and since the former set is fixed to the main member 1 and the latter ones are fixed to the long thin members 110 and 112, members 98 and 100 can move in a limited arcuate matter about pins 106 and 108. It would also be appreciated that since member 1 is stationary with respect to this mechanism, movement of members 98 and 100 will cause the movement of members 110 and 112. This in turn because of the interconnection between these long members and the printing head shaft by means of pins 115 and 116 will cause the vertical movement of the printing head to shift it from one band to the other. Pins 115 and 116 fit into a groove in the shaft that supports the printing head. The vertical movement of these pins will cause the corresponding vertical movement of the printing. To permit members 110 and 1 12 to move without having pins 106 and 108, which pass through them, interfere with that movement the pins fit through large oval openings 111 and 113 in the members. This permits sufficient movement of the members without interference from the pins. Also, to provide sufficient strength around these openings the width of the members is expanded around the openings with arcuate sections of material 115 and 117 as shown in FIG. 3.

Basically the operation of the mechanism is as follows: As shown in FIG. 5 when electromagnets-SZ and 53 are activated, members 98 and 100 will move respectively downwardly and upwardly as shown in FIG. 5 to form a straight line and thereby cause members 110 and 112 to assume a position wherein the part closest to the print head is in a generally upwardly extending position. This will move the print head shaft and the print head to its highest position as shown in FIG. 5 to thereby align the lowest band of type on the print head with the platen.

The next lowest band of type is aligned as shown in FIG. 6. This is done by the actuation of electromagnets 51 and 52. The actuation of these electromagnets will cause members 98 and 100 to be attracted upwards and thereby cause members l 10 and 1 12 to assume a somewhat horizontal configuration with the part closest to the print head tilted slightly downwardly. This as aforementioned, will cause the next to lowest band of the printing head to be placed in printing position with the platen.

To cause the next to highest band of the print head to be placed in printing position, electromagnets S3 and 54 are actuated. This willcause members 98 and 100 to be attracted downwardly and thereby align members 1 l0 and 112 in a position wherein the part of members 1 10 and l 12 closest to the print head is tilted slightly upwardly with respect to the horizontal. This as aforementioned, will cause the print head to drop slightly down from the position of FIG. 6 so that the next to highest band is aligned with the printing position as shown in FIG. 7.

The last and highest position is shown in FIG. 8. To move the printing head to this position electromagnets 51 and 54 are actuated. This will cause member 98 to be attracted upwardly and member 100 to be attracted downwardly. Members 112 and 110 will then assume a downwardly projecting position which is exactly the opposite of the position of FIG. 5 and thereby cause the printing head to be in the lowest position and the top printing band to be aligned with the platen.

Thus, by the actuation of these four electromagnets and the use of the linkage as previously described, all four bands of the printing head can quickly be brought into alignment with the printing platen. To assist in this movement four springs are provided. These springs are balanced so that they exert the same force on respective sides of the center linkage. This will cause the center linkage to always return to its central position when all four electromagnets are not actuated.

In operation however, as one electromagnet is actuated the spring alongside its opposing electromagnet (on the other side of the central linkage) will be stretched to impart potential energy to it. In other words, if electromagnet 53 is actuated spring 95 alongside the electromagnet 51 will be stretched and thereby have potential energy imparted to it. Then when electromagnet 51 is actuated and electromagnet 53 deactuated the potential energy in the spring will assist in moving the central linkage towards electromagnet 5 1 and away from electromagnet 53 to thereby increase the speed of operation of the mechanism. The combination of these springs and electromagnets provides a very efficient and rapidly operating mechanism.

It is now apparent that the invention attains the objects set forth. Apparatus embodying the invention is study in construction and well adapted for use in high speed printers.

A specific embodiment of the invention has been illustrated but the invention'is not limited thereto since many modifications can be -made by one skilled in the art that falls within the true spirit and scope of the invention.

I claim:

1. A device for shifting a print member between a plurality of type bands comprising:

a print member having a plurality of print bands,

a support member,

a first member connected to said print member mounted to shift said print member between said type bands,

a second member pivotably connected to said first member and to said support member,

a third member pivotably connected to said first member and to said support member so that said second and third members can pivot with respect to said support member and thereby shift said first member,

said second and third members each having one end which is proximate to each other and each having another end which is distal each other, said second and third members being mounted so that their ends proximate each other are respectively pivotably affixed to said support member and their ends 6 distal each other are pivotably connected to said first member, and

a plurality of electromagnets mounted to attract said second and third members and thereby cause them to pivot about said support member and' thereby cause said first member to shift from one type band to another.

2. The device of claim 1 wherein said second and third members are mounted so that the electromagnets are positioned on each side of said second member and each side of said third member and proximate the pivotial connection of said second and third members respectively to said first member so that said second and third members may be attracted to said electromagnets to thereby shift the position of said first member and thereby shift the print member.

3. The device of claim 2 wherein said second and third member are constructed of magnetically attractable material.

4. The device of claim 3 wherein in a normal position wherein said electromagnets are unactuated said second and third member and said first member are essentially in the same plane.

5. The device of claim 4 wherein springs are provided between said second and third members and said support member respectively to aid in said shifting movement.

6. The device of claim 5 wherein 7 said print member has four type bands, highest to lowest, thereon and wherein the actuation of said electromagnets on one side, a first side, of said second member and on an opposite side, a second side, of said third member causes said first member to shift said print head into a position wherein said print head is in a highest position and the lowest type band is in a printing position.

7. The device of claim 6 wherein the actuation of said electromagnets on one side, a first side, of said second member and on the same side, a first side, of said third member causes said first member to shift said print head into a position wherein said print head is in a next to highest position and the next to lowest type band is in a printing position.

8. The device of claim 7 wherein the actuation of said electromagnets on a second side of said second member and on said second side of said third member cause said first member to shift said print head into a position wherein said print head is in a next to lowest position and the next to highest type band is in printing position.

9. The device of claim 8 wherein the actuation of said electromagnets on the first side of said second member and on said second side of said third member cause said first member to shift said print head into a position wherein said print head is in a lowest portion and the highest type band is in printing position.

10. A device for shifting a print member between a plurality of type bands comprising:

a print member having four type bands,

a support member,

a first member connected to said print member mounted to shift said print member between said type bands,

a second member pivotably connected to said first member and to said support member, for movement in a first plane,

a third member pivotably connected to said first member and to said support member, for movement in said first plane, so that said second and third members can pivot with respect to said support member in the same plane and thereby shift said first member, and

a plurality of electromagnets mounted to attract said second and third members and thereby cause them to pivot about said support member and thereby cause said first member to shift from one type band to another, including two pair of opposed electromagnets,

a first pair of opposed springs connected to said second member and coplanar with said first plane for normally equally biasing the same in opposite directions, and

a second pair of opposed springs connected to said third member and coplanar with said first plane for normally equally biasing the same in opposite directions.

11. A device for shifting a print member between a plurality of type bands comprising:

a print member,

a support member,

a first member connected to said print member mounted to shift said print member between said type bands,

a second member connected to said first member and to said support member for limited arcuate movement,

a third member connected to said first member and to said support member for limited arcuate movement,

said second and third members being moveable with respect to said support member to thereby shift said first member, moveable with respect to said support member, and wherein one end of each of said second and third members being connected to said support solely through said first member, and

a plurality of electromagnets mounted to attract said second and third members and thereby cause them to move about said support member. 

1. A device for shifting a print member between a plurality of type bands comprising: a print member having a plurality of print bands, a support member, a first member connected to said print member mounted to shift said print member between said type bands, a second member pivotably connected to said first member and to said support member, a third member pivotably connected to said first member and to said support member so that said second and third members can pivot with respect to said support member and thereby shift said first member, said second and third members each having one end which is proximate to each other and each having another end which is distal each other, said second and third members being mounted so that their ends proximate each other are respectively pivotably affixed to said support member and their ends distal each other are pivotably connected to said first member, and a plurality of electromagnets mounted to attract said second and third members and thereby cause them to pivot about said support member and thereby cause said first member to shift from one type band to another.
 2. The device of claim 1 wherein said second and third members are mounted so that the electromagnets are positioned on each side of said second member and each side of said third member and proximate the pivotial connection of said second and third members respectively to said first member so that said second and third members may be attracted to said electromagnets to thereby shift the position of said first member and thereby shift the print member.
 3. The device of claim 2 wherein said second and third member are constructed of magnetically attractable material.
 4. The device of claim 3 wherein in a normal position wherein said electromagnets are unactuated said second and third member and said first member are essentially in the same plane.
 5. The device of claim 4 wherein springs are provided between said second and third members and said support member respectively to aid in said shifting movement.
 6. The device of claim 5 wherein said print member has four type bands, highest to lowest, thereon and wherein the actuation of said electromagnets on one side, a first side, of said second member and on an opposite side, a second side, of said third member causes said first member to shift said print head into a position wherein said print head is in a highest position and the lowest type band is in a printing position.
 7. The device of claim 6 wherein the actuation of said electromagnets on one side, a first side, of said second member and on the same side, a first side, of said third member causes said first member to shift said print head into a position wherein said print head is in a next to hiGhest position and the next to lowest type band is in a printing position.
 8. The device of claim 7 wherein the actuation of said electromagnets on a second side of said second member and on said second side of said third member cause said first member to shift said print head into a position wherein said print head is in a next to lowest position and the next to highest type band is in printing position.
 9. The device of claim 8 wherein the actuation of said electromagnets on the first side of said second member and on said second side of said third member cause said first member to shift said print head into a position wherein said print head is in a lowest portion and the highest type band is in printing position.
 10. A device for shifting a print member between a plurality of type bands comprising: a print member having four type bands, a support member, a first member connected to said print member mounted to shift said print member between said type bands, a second member pivotably connected to said first member and to said support member, for movement in a first plane, a third member pivotably connected to said first member and to said support member, for movement in said first plane, so that said second and third members can pivot with respect to said support member in the same plane and thereby shift said first member, and a plurality of electromagnets mounted to attract said second and third members and thereby cause them to pivot about said support member and thereby cause said first member to shift from one type band to another, including two pair of opposed electromagnets, a first pair of opposed springs connected to said second member and coplanar with said first plane for normally equally biasing the same in opposite directions, and a second pair of opposed springs connected to said third member and coplanar with said first plane for normally equally biasing the same in opposite directions.
 11. A device for shifting a print member between a plurality of type bands comprising: a print member, a support member, a first member connected to said print member mounted to shift said print member between said type bands, a second member connected to said first member and to said support member for limited arcuate movement, a third member connected to said first member and to said support member for limited arcuate movement, said second and third members being moveable with respect to said support member to thereby shift said first member, moveable with respect to said support member, and wherein one end of each of said second and third members being connected to said support solely through said first member, and a plurality of electromagnets mounted to attract said second and third members and thereby cause them to move about said support member. 